Like a lot of other folks, i have been shooting 2 3/4 shells in short chambers with no problems. Caveat that they are low pressure loads (mine) using one of Joe Woods recipes. BUT the lil 16 hammer gun I just picked up will NOT allow a 2 3/4 inch shell to be chambered, without a great deal of force being applied...It will shoot short RST's as long as I have it...